Spider Stellar Engine: The Heating and Exhaust Cycle

A long-lived civilization will inevitably have to migrate towards a nearby star as its home star runs out of nuclear fuel. Although it sounds like science fiction, one way to achieve such a migration is by transforming its star into a stellar engine, and to control its motion in the galaxy. Technosignatures of stellar engines has taken two roads: on the observational side, hypervelocity stars have been the target of such searches, but without good candidates (Lingam and Loeb 2020). On the theoretical side, stellar engine concepts have been proposed (Shkadov 1988; Fogg 1989; Caplan 2019; Svoronos 2020) but are poorly linked to observable technosignatures. Since about half the stars in our galaxy are in binary systems where life might develop too, we focus on a model of a binary stellar engine (Vidal 2024).

We apply the model to candidate systems, spider pulsars, which are binary stars composed of one millisecond pulsar and a very low-mass companion star that is heavily irradiated by the pulsar wind. From this stellar engineering perspective, we propose a new interpretation for the observed average Gamma-ray orbital modulated fraction of about 22% (Satybaldiev et al. 2025). We also propose a new interpretation of the often-observed anti-correlation between Gamma-ray and X-ray modulation (occurring respectively at phase 0.25 and 0.75) in terms of a stellar engine cycle alternating between a heating phase (X-rays) and an exhaust phase (Gamma-rays). We summarize observations, astrophysical interpretations, artificial interpretations, and propose avenues for tests. 

References:

Caplan, Matthew E. 2019. “Stellar Engines: Design Considerations for Maximizing Acceleration.” Acta Astronautica 165 (December): 96–104. https://doi.org/10.1016/j.actaastro.2019.08.027.

Fogg, Martyn J. 1989. “Solar Exchange as a Means of Ensuring the Long Term Habitability of the Earth.” Speculations in Science and Technology 12 (2): 153.

Lingam, Manasvi, and Abraham Loeb. 2020. Constraints on the Abundance of 0.01 c Stellar Engines in the Milky Way. 905 (2): 175. https://doi.org/10.3847/1538-4357/abc69c.

Satybaldiev, Maksat, Manuel Linares, and Vittoria Vecchiotti. 2025. “Gamma-Ray Orbital Modulation in Spider Pulsars: Three Discoveries and a Universal Modulated Fraction.” arXiv:2510.11699. Version 1. Preprint, arXiv, October 13. https://doi.org/10.48550/arXiv.2510.11699.

Shkadov, L. M. 1988. “Possibility of Control of Galactic Motion of the Solar System.” Solar System Research 22 (January): 210–14. https://ui.adsabs.harvard.edu/abs/1988SoSyR..22..210S.

Svoronos, Alexander A. 2020. “The Star Tug: An Active Stellar Engine Capable of Accelerating a Star to Relativistic Velocities.” Acta Astronautica 176 (November): 306–12. https://doi.org/10.1016/j.actaastro.2020.07.005.

Vidal, C. 2024. “The Spider Stellar Engine: A Fully Steerable Extraterrestrial Design?” Journal of the British Interplanetary Society 77 (5): 156–66. https://doi.org/10.48550/arXiv.2411.05038.